Leviathan Patera

Leviathan Patera is a large cryovolcanic caldera on Triton, Neptune’s biggest moon. It was first seen by the Voyager 2 probe during its 1989 flyby and sits in Monad Regio, within the western part of Cipango Planum. The caldera measures about 80 kilometers across and could mark the center of one of the largest cryovolcanic structures in the Solar System.

Discovery and naming

The feature was named after the Leviathan, a sea serpent from Hebrew scripture, and the International Astronomical Union officially approved the name in 1991.

Geology

Geologically, Leviathan Patera is a steep-sided depression with several curved scarps, closely resembling terrestrial collapse calderas. Its northern half has a mostly flat floor about 450 meters deep, broken by an irregular plateau. The southern half is taken up by a broad dome roughly 400 meters high, nearly level with the surrounding plains.

A high point in the northwestern section rises about 1 kilometer, one of the tallest local elevations. Around the caldera runs a ring of very smooth terrain, carved by outward-facing arcuate alcoves. Nearby lie two major tectonic features, Kraken Catena and Set Catena, suggesting that rifting at the site is closely tied to the caldera’s formation and activity.

Leviathan Patera appears to be the central vent of Cipango Planum, a geologically young plateau built from cryovolcanic material. Eruptions of cryolava from the caldera constructed much of this plateau and the smooth terrain around it.

If Cipango Planum is part of the same edifice, Leviathan Patera is the largest known cryovolcano on Triton and among the largest volcanic features in the Solar System. Its eruptive history likely occurred in stages: first, low-viscosity cryolava resurfaced the surrounding plains, giving Cipango Planum its shallow relief; then eruptions became explosive; finally, higher-viscosity material built domes inside the caldera. Little collapse has happened in the caldera’s center, and apparent explosion pits surround a ring fracture.